Bicocca Open Archive

Sulfur disproportionation in deep COHS slab fluids drives mantle wedge oxidation

Sulfur degassed at volcanic arcs calls for dissolved sulfate ions (S6+) released by subduction-zone fluids, oxidizing (in association with carbon) the subarc mantle, but sulfur speciation in subduction fluids at subarc depths remains unclear. We apply electrolytic fluid thermodynamics to model the dissolution behavior of pyrite in metacarbonate sediments as a function of P, T and rock redox state up to 4.3 gigapascals and 730°C. At subarc depth and the redox conditions of the fayalite-magneti...

Quantitative Study of the Stabilization Parameter in the Virtual Element Method

The choice of stabilization term is a critical component of the virtual element method (VEM). However, the theory of VEM provides only asymptotic guidance for selecting the stabilization term, which ensures convergence as the mesh size approaches zero, but does not provide a unique prescription for its exact form. Thus, the selection of a suitable stabilization term is often guided by numerical experimentation and analysis of the resulting solution, including factors such as stability, accura...

Curvilinear Mesh Generation for the High-Order Virtual Element Method (VEM)

We present a proof-of-concept methodology for generating curvilinear polygonal meshes suitable for high-order discretizations by the Virtual Element Method (VEM). A VEM discretization requires the definition of a set of boundary and internal points that are used to interpolate the approximation functions and to evaluate integrals by means of suitable quadratures. The procedure to locate these points on the boundary borrows ideas from previous work on a posteriori high-order mesh generation in...

Oltre la microfondazione: Esiste una “terza via”?